Darpa Implants Could Track Your Stress Level 24/7

Plenty of geeks are already obsessed with self-tracking, from monitoring sleep rhythms to graphing caffeine intake versus productivity. Now, the Department of Defense’s far-out research agency is after the ultimate kind of Quantified Self: Soldiers with implanted body sensors that keep intimate tabs on their health, around the clock.

In a new call for research, Darpa is asking for proposals to devise prototype implantable biosensors. Once inserted under a soldier’s skin, Darpa wants the sensors to provide real-time, accurate measurements of “DoD-relevant biomarkers” including stress hormones, like cortisol, and compounds that signal inflammation, like histamine.

Implantable sensors are only the latest of several Pentagon-backed ventures to track a soldier’s health. Darpa’s already looked into tracking “nutritional biomarkers” to evaluate troops’ diets. And as part of the agency’s “Peak Soldier Performance” program, Darpa studied how one’s genes impact physical ability, and tried to manipulate cellular mitochondria to boost the body’s energy levels.

Sensors alone won’t make troops stronger, smarter or more resilient. But they’d probably offer the kind of information that could. For one thing, the sensors would provide military docs an array of reliable info about the health of every single soldier. Plus, they’d tell leaders how a soldier’s body stood up to grueling physical training or a tough deployment. Tracking changes in the body’s endocrine system, for example, might tell a physician that a soldier is increasingly sleep deprived. Or observing chronically increased inflammation levels might tell a team leader that trainee number five isn’t cut out for the Navy SEALs.

Real-time sensors would also solve plenty of problems where warzone medical care is concerned. It’s not easy to take a urine test in the middle of a firefight. Darpa’s solicitation notes that health care often suffers because of “overnight shipping to a centralized laboratory,” and the “collection, processing and handling” that can mar specimens in transit.

Besides, urine samples and blood tests are hardly as personalized as an implanted sensor would be. A system that tracks several biomarkers could offer a robust and real-time analysis of how, say, a soldier’s sleeping patterns or dietary choices affect his or her physical performance.

Far out as the idea sounds, scientists have already made impressive strides toward implantable biosensors. A team at Clemson University, with Pentagon funding, has devised a sensor that can be implanted for short periods to monitor the well being of injured patients. Another group, at Tufts University, is making biosensors out of silk, which they think will be easier to introduce into bodily tissues. Some companies are even getting into niche implants, most notably those to monitor glucose levels among diabetics.

Still, plenty of challenges persist. For one, biocompatibility — the ability of the sensor to integrate into the body, without being “walled off” by surrounding tissues — is still a limiting factor in determining whether a sensor will even work, not to mention what it can measure and how long it’ll last. And Darpa’s ideal sensors don’t just need to be biocompatible. They’ve also got to offer extremely accurate information on several different biomarkers, and have a long enough lifespan to avoid frequent replacement.

Of course, a sensor that tracked every estrogen uptick and cortisol dip would be a self-tracker’s wet dream and a major aide for doctors — whether civilian or military. It’s also got some vaguely dystopian connotations, like the prospect of job hiring and firing based on, say, a body that’s got less than optimal stress responses.

But don’t panic just yet. For now, Darpa only wants prototypes tested on “biospecimens and animal models.”